Data communication systems typically utilize a transmitting device that operates under control of a first clock and an independent receiving device that operates under control of a second clock. Although the first clock and the second clock may be designed to operate at exactly the same desired frequency, the reality is that there is clock speed variation associated with each clock. Therefore, the transmitting device and the receiving device have a clock rate difference. This clock rate difference causes the receiver to see the incoming data at either faster or slower than expected, hereafter referred to as “timing drifting”, thus being unable to properly acknowledge and process the data.
In packet based transmission systems, generally there is a known synchronization bit pattern that allows a receiver to recognize the beginning of a packet transmission. For packet based communication systems, if the amount of the maximum possible timing drift during the packet is much smaller than a symbol period, then this clock rate difference can be ignored. However, for a communication system with high symbol rate and long packet size, such as the Bluetooth High Rate and the 802.11b standards, the timing drift creates significant data errors. Patenaude et al. disclosed in “A New Symbol Timing Tracking Algorithm for π/2-BPSK and π/4-QPSK Modulations” in the ICC Proceedings, pages 1588–1592 (1992), a technique for implementing timing tracking in a communication system. The approach proposed by Patenaude et al. is complex and requires a significant amount of hardware and calculations. Therefore, power consumption and the cost of the tracking circuitry are significant deterrents to using Patenaude's approach.
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